option.go

// Copyright 2021 PingCAP, Inc.

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package kv

import (
	"context"

	"github.com/pingcap/errors"
	"github.com/tikv/client-go/v2/util"
)

// Transaction options
const (
	// BinlogInfo contains the binlog data and client.
	BinlogInfo int = iota + 1
	// SchemaChecker is used for checking schema-validity.
	SchemaChecker
	// IsolationLevel sets isolation level for current transaction. The default level is SI.
	IsolationLevel
	// Priority marks the priority of this transaction.
	Priority
	// NotFillCache makes this request do not touch the LRU cache of the underlying storage.
	NotFillCache
	// SyncLog is not used anymore.
	SyncLog
	// KeyOnly retrieve only keys, it can be used in scan now.
	KeyOnly
	// Pessimistic is defined for pessimistic lock
	Pessimistic
	// SnapshotTS is defined to set snapshot ts.
	SnapshotTS
	// Set replica read
	ReplicaRead
	// Set task ID
	TaskID
	// InfoSchema is schema version used by txn startTS.
	InfoSchema
	// CollectRuntimeStats is used to enable collect runtime stats.
	CollectRuntimeStats
	// SchemaAmender is used to amend mutations for pessimistic transactions
	SchemaAmender
	// SampleStep skips 'SampleStep - 1' number of keys after each returned key.
	SampleStep
	// CommitHook is a callback function called right after the transaction gets committed
	CommitHook
	// EnableAsyncCommit indicates whether async commit is enabled
	EnableAsyncCommit
	// Enable1PC indicates whether one-phase commit is enabled
	Enable1PC
	// GuaranteeLinearizability indicates whether to guarantee linearizability at the cost of an extra tso request before prewrite
	GuaranteeLinearizability
	// TxnScope indicates which @@txn_scope this transaction will work with.
	TxnScope
	// ReadReplicaScope
	ReadReplicaScope
	// StalenessReadOnly indicates whether the transaction is staleness read only transaction
	IsStalenessReadOnly
	// MatchStoreLabels indicates the labels the store should be matched
	MatchStoreLabels
	// ResourceGroupTag indicates the resource group tag of the kv request.
	ResourceGroupTag
	// ResourceGroupTagger can be used to set the ResourceGroupTag dynamically according to the request content. It will be used only when ResourceGroupTag is nil.
	ResourceGroupTagger
	// KVFilter indicates the filter to ignore key-values in the transaction's memory buffer.
	KVFilter
	// SnapInterceptor is used for setting the interceptor for snapshot
	SnapInterceptor
	// CommitTSUpperBoundChec is used by cached table
	// The commitTS must be greater than all the write lock lease of the visited cached table.
	CommitTSUpperBoundCheck
	// RPCInterceptor is interceptor.RPCInterceptor on Transaction or Snapshot, used to decorate
	// additional logic before and after the underlying client-go RPC request.
	RPCInterceptor
	// TableToColumnMaps is a map from tableID to a series of maps. The maps are needed when checking data consistency.
	// Save them here to reduce redundant computations.
	TableToColumnMaps
	// AssertionLevel controls how strict the assertions on data during transactions should be.
	AssertionLevel
	// RequestSourceInternal set request source scope of transaction.
	RequestSourceInternal
	// RequestSourceType set request source type of the current statement.
	RequestSourceType
	// ReplicaReadAdjuster set the adjust function of cop requsts.
	ReplicaReadAdjuster
	// ScanBatchSize set the iter scan batch size.
	ScanBatchSize
	// TxnSource set the source of this transaction.
	// We use an uint64 to represent the source of a transaction.
	// The first 8 bits are reserved for TiCDC to implement BDR synchronization,
	// and the next 8 bits are reserved for Lossy DDL reorg Backfill job.
	// The remaining 48 bits are reserved for extendability.
	TxnSource
	// ResourceGroupName set the bind resource group name.
	ResourceGroupName
	// LoadBasedReplicaReadThreshold sets the TiKV wait duration threshold of enabling replica read automatically.
	LoadBasedReplicaReadThreshold
)

// ReplicaReadType is the type of replica to read data from
type ReplicaReadType byte

const (
	// ReplicaReadLeader stands for 'read from leader'.
	ReplicaReadLeader ReplicaReadType = iota
	// ReplicaReadFollower stands for 'read from follower'.
	ReplicaReadFollower
	// ReplicaReadMixed stands for 'read from leader and follower'.
	ReplicaReadMixed
	// ReplicaReadClosest stands for 'read from leader and follower which locates with the same zone'
	ReplicaReadClosest
	// ReplicaReadClosestAdaptive stands for 'read from follower which locates in the same zone if the response size exceeds certain threshold'
	ReplicaReadClosestAdaptive
	// ReplicaReadLearner stands for 'read from learner'.
	ReplicaReadLearner
	// ReplicaReadPreferLeader stands for 'read from leader and auto-turn to followers if leader is abnormal'.
	ReplicaReadPreferLeader
)

// IsFollowerRead checks if follower is going to be used to read data.
func (r ReplicaReadType) IsFollowerRead() bool {
	return r != ReplicaReadLeader
}

// IsClosestRead checks whether is going to request closet store to read
func (r ReplicaReadType) IsClosestRead() bool {
	return r == ReplicaReadClosest
}

// RequestSourceKey is used as the key of request source type in context.
var RequestSourceKey = util.RequestSourceKey

// RequestSource is the scope and type of the request and it's passed by go context.
type RequestSource = util.RequestSource

// WithInternalSourceType create context with internal source.
var WithInternalSourceType = util.WithInternalSourceType

// GetInternalSourceType get internal source
func GetInternalSourceType(ctx context.Context) string {
	v := ctx.Value(util.RequestSourceKey)
	if v == nil {
		return ""
	}
	return v.(util.RequestSource).RequestSourceType
}

const (
	// InternalTxnOthers is the type of requests that consume low resources.
	// This reduces the size of metrics.
	InternalTxnOthers = util.InternalTxnOthers
	// InternalTxnGC is the type of GC txn.
	InternalTxnGC = util.InternalTxnGC
	// InternalTxnBootstrap is the type of TiDB bootstrap txns.
	InternalTxnBootstrap = InternalTxnOthers
	// InternalTxnMeta is the type of the miscellaneous meta usage.
	InternalTxnMeta = util.InternalTxnMeta
	// InternalTxnDDL is the type of inner txns in ddl module.
	InternalTxnDDL = "ddl"
	// InternalTxnBackfillDDLPrefix is the prefix of the types of DDL operations needs backfilling.
	InternalTxnBackfillDDLPrefix = "ddl_"
	// InternalTxnCacheTable is the type of cache table usage.
	InternalTxnCacheTable = InternalTxnOthers
	// InternalTxnStats is the type of statistics txn.
	InternalTxnStats = "stats"
	// InternalTxnBindInfo is the type of bind info txn.
	InternalTxnBindInfo = InternalTxnOthers
	// InternalTxnSysVar is the type of sys var txn.
	InternalTxnSysVar = InternalTxnOthers
	// InternalTxnTelemetry is the type of telemetry.
	InternalTxnTelemetry = InternalTxnOthers
	// InternalTxnAdmin is the type of admin operations.
	InternalTxnAdmin = "admin"
	// InternalTxnPrivilege is the type of privilege txn.
	InternalTxnPrivilege = InternalTxnOthers
	// InternalTxnTools is the type of tools usage of TiDB.
	// Do not classify different tools by now.
	InternalTxnTools = "tools"
	// InternalTxnBR is the type of BR usage.
	InternalTxnBR = InternalTxnTools
	// InternalTxnTrace handles the trace statement.
	InternalTxnTrace = "Trace"
	// InternalTxnTTL is the type of TTL usage
	InternalTxnTTL = "TTL"
	// InternalLoadData is the type of LOAD DATA usage
	InternalLoadData = "LoadData"
	// InternalDistTask is the type of distributed task.
	InternalDistTask = "DistTask"
)

// The bitmap:
// |RESERVED|LOSSY_DDL_REORG_SOURCE_BITS|CDC_WRITE_SOURCE_BITS|
// |  48    |             8             | 4(RESERVED) |  4    |
const (
	// TiCDC uses 1 - 255 to indicate the source of TiDB.
	// For now, 1 - 15 are reserved for TiCDC to implement BDR synchronization.
	// 16 - 255 are reserved for extendability.
	cdcWriteSourceBits = 8
	cdcWriteSourceMax  = (1 << cdcWriteSourceBits) - 1

	// TiCDC uses 1-255 to indicate the change from a lossy DDL reorg Backfill job.
	// For now, we only use 1 for column reorg backfill job.
	lossyDDLReorgSourceBits   = 8
	LossyDDLColumnReorgSource = 1
	lossyDDLReorgSourceMax    = (1 << lossyDDLReorgSourceBits) - 1
	lossyDDLReorgSourceShift  = cdcWriteSourceBits
)

// SetCDCWriteSource sets the TiCDC write source in the txnSource.
func SetCDCWriteSource(txnSource *uint64, value uint64) error {
	if value > cdcWriteSourceBits {
		return errors.Errorf("value %d is out of TiCDC write source range, should be in [1, 15]",
			value)
	}
	*txnSource |= value

	return nil
}

func getCDCWriteSource(txnSource uint64) uint64 {
	return txnSource & cdcWriteSourceMax
}

func isCDCWriteSourceSet(txnSource uint64) bool {
	return (txnSource & cdcWriteSourceMax) != 0
}

// SetLossyDDLReorgSource sets the lossy DDL reorg source in the txnSource.
func SetLossyDDLReorgSource(txnSource *uint64, value uint64) error {
	if value > lossyDDLReorgSourceMax {
		return errors.Errorf("value %d is out of lossy DDL reorg source range, should be in [1, %d]",
			value, lossyDDLReorgSourceMax)
	}
	*txnSource |= value << lossyDDLReorgSourceShift

	return nil
}

func getLossyDDLReorgSource(txnSource uint64) uint64 {
	return (txnSource >> lossyDDLReorgSourceShift) & lossyDDLReorgSourceMax
}

func isLossyDDLReorgSourceSet(txnSource uint64) bool {
	return (txnSource >> lossyDDLReorgSourceShift) != 0
}